Four years, he spent there. Four fun, fulfilling years in America's Deep South. But when his time was up, when Seán Tobin finally left Mississippi, he couldn't dislodge a troubling thought.

"I felt like a failure," he says. "It was one of the darkest times. I was at home and just miserable - didn't know where I was going, my parents didn't know what to do with me, and I was really lost."

In Irish athletics, there is a never-ending debate about the US scholarship trail. Its proponents point to its record in forging so many great careers - Sonia O'Sullivan, Ronnie Delany, Eamonn Coghlan - but its critics counter that they were simply the eggs that didn't crack, that the mass wastage elsewhere exists in anonymous regret, their stories untold.

But chisel into Tobin's tale and you realise it's not so much the college years that count, but what comes after.

Now that he's back home, he can see that void, the great abyss into which so many talented athletes fall once the working world gets them in its clutch. Nine-to-fives, commutes, rip-off rents - the steady erosion of essential energy.

"A lot of Irish athletes are like that," says Tobin. "There is no support system for when they come home and that's not bashing the federation - they do the best with what they have - but when you come home you realise their budget is nothing."

Not compared to what's out there, that river of revenue flowing through the NCAA system.

Wide-eyed

Tobin can remember his first trip to the US - a weekend at the University of Mississippi; how he was whisked from the plane straight to a college football game, his wide-eyed wonder at 60,000 screaming souls. "Small town, decent-sized school, beautiful campus," he says.

He set off in January 2014, leaving Clonmel and a promising junior career behind to start a new life in Oxford, Mississippi.

Guns, trucks, hunting, country music - it took some adjusting, but Tobin learned to love its quirky ways.

One year he even moved off campus with his team-mates, finding a house in the sticks where they reared chickens, logged 100-mile weeks and, in the absence of any internet, learned to converse without typing into a phone. He loved it, cherished it.

But not all of it. There was the time he snapped his metatarsal in the first kilometre of the NCAA Cross Country. "After the race none of my teammates cared about the result, they were upset I had broken my foot and that was the first sign I'd chosen the right place - they were there for me."

The loneliness? That came after he left. Tobin's final year never rose much above lukewarm, at least by his standards, and in a desperate bid to earn a professional contract he ran 120 miles a week, ultimately frying his system.

"I wanted it too much," he admits. "The end left a sour taste in my mouth because I felt the pressure of trying to get a contract, knowing it was my last year."

Out of options, he returned to Clonmel, but between mediocre races over the summer he would twiddle his thumbs, wondering what to do with his life, his talent. No income, no career and no real hope.

It was then a message arrived from Feidhlim Kelly, a coach who had put together the leading middle-distance group in the country under the umbrella of the Dublin Track Club. He extended an invite for Tobin to pay a visit.

Spooky

"It sounds very American, like a movie, but it was spooky how the message came up at that very moment," says Tobin. "I was like, 'f*** it, this is an opportunity'."

Kelly reviewed his training diaries, spotted several areas for improvement, and encouraged Tobin to move to Dublin, even offering up his own room in Santry.

Without any income Tobin was hesitant, but it was then that Richard Donovan, a race organiser with Global Running Adventures, offered Tobin some financial backing in his bid to make the 2020 Olympics.

And so it was through part luck, part generosity, that Tobin has been able to commit full-time to running, and as such he arrives at tomorrow's National Cross Country Championships as the favourite.

Last year he finished 15th at the European Cross Country Championships and if all goes well in the coming weeks, he could be set for an even bigger showing at this year's edition in the Netherlands on December 9.

After that he'll set off for Australia, where for two months he'll train under the eye of one of Kelly's good friends, Nic Bideau, who oversees a group of world-class distance runners at the Melbourne Track Club.

"I want to see what it takes and then take that home - to change the culture of Irish distance running."

If he has one regret about America, it's that he didn't focus more on academics, though Tobin plans to add to his general studies degree with a master's in business in the coming years. He had thought about committing to it this year, but then thought, no, actually, that can wait - at least until 2020.

"I decided for what I'm going for - Tokyo," he says. "I may as well go all in."